I. Field of the Invention
The present invention relates to a magnetic recording/reproducing apparatus using a cassette tape and, more particularly, to a magnetic recording/repro-ducing apparatus wherein a cassette tape inserted therein is moved downward at a predetermined position and set so as to perform recording or reproduction.
II. Description of the Prior Art
FIGS. 1 to 3 show a conventional magnetic recording/reproducing apparatus. Referring to FIGS. 1 to 3, reference numeral 1 denotes a chassis. Side plates 2L and 2R are integrally formed at both sides of the chassis 1. Reference numerals 3L and 4L, and 3R and 4R denote guide holes which are vertically formed in the side plates 2L and 2R, respectively, and extend in a direction perpendicular to the surface of chassis 1. Reference numerals 5L and 5R denote cassette holders for guiding and holding a cassette 6 inserted therein. Pins 7L and 8L and pins 7R and 8R formed on the cassette holders 5L and 5R are inserted in the guide holes 3L and 4L and 3R and 4R, respectively. The cassette holders 5L and 5R are respectively guided by the guide holes 3L and 4L, and 3R and 4R, so as to be vertically moved. Reference numerals 9L and 9R denote arms which are supported to be pivotal about pins 10L and 10R formed on the side plates 2L and 2R, respectively. An elongated hole 11L is formed at one end of the arm 9L, and an elongated hole 11R is formed at one end of the arm 9R. An engaging pawl 12L is formed at the other end of the arm 9L, and an engaging pawl 12R is formed at the other end of the arm 9R. The pins 8L and 8R of the cassette holders 5L and 5R are inserted in the elongated holes 11L and 11R of the arms 9L and 9R through the guide holes 4L and 4R, respectively. Reference numerals 13L and 13R denote link arms supported to be pivotal about pins 14L and 14R formed on the side plates 2L and 2R, respectively. Notched steps 15L and 15R, elongated holes 16L and 16R, and engaging members 17L and 17R are formed on the link arms 13L and 13R, respectively. The pins 7L and 7R of the cassette holders 5L and 5R extend through the guide holes 3L and 3R of the side plates 2L and 2R and are inserted in the elongated holes 16L and 16R of the link arms 13L and 13R, respectively.
Referring to FIG. 3, reference numeral 18 denotes an eject lever. The eject lever 18 is slidably supported by pins which extend from the chassis 1. Reference numerals 19L and 19R, respectively, denote projections integrally formed with the left and right ends of the eject lever 18. Reference numerals 20L and 20R denote pivot arms, respectively. One end portion of each of the pivot arms 20L and 20R is bent in a substantially U shape. A hole 21L is formed at one end portion of the pivot arm 20L, and a hole 21R is formed at one end portion of the pivot arm 20R. Reference numerals 22L and 22R respectively denote shafts fixed on the chassis 1. The shafts 22L and 22R are inserted in the holes 21L and 21R of the pivot arms 20L and 20R. The pivot arms 20L and 20R are pivotal around the shafts 22L and 22R, respectively. Reference numerals 23L and 23R denote bent members formed at the free end portions (i.e., the other end portion) of the pivot arms 20L and 20R, respectively. Reference numerals 24L and 24R denote L-shaped engaging members integrally formed with the pivot arms 20L and 20R, respectively. Reference numeral 25 denotes a connecting rod, both ends of which are screwed to the link arms 13L and 13R. Reference numeral 26 denotes a spring mounted around the shaft 22R. One end of the spring 26 engages with the pivot arm 20R and the other end thereof engages with the upright member formed on the chassis 1. The pivot arm 20R is biased counterclockwise by the biasing force of the spring 26. Reference numerals 27L and 27R denote springs, respectively. One end of each of the springs 27L and 27R engages with a corresponding one of the engaging members 17L and 17R of the link arms 13L and 13R, and the other end thereof engages with a corresponding one of engaging members 28L and 28R of the chassis 1. The link arms 13L and 13R are biased counterclockwise by the springs 27L and 27R, respectively. Reference numeral 29 denotes an elongated hole formed in the pivot arm 20L; and 30, a pin. The pin 30 extends through the elongated hole 29 and is forcibly inserted in a hole 31 of the pivot arm 20R.
Referring to FIGS. 1 and 2, reference numeral 40 denotes an operation button fixed on the eject lever 18. One end of each of springs 41L and 41R engages with the eject lever 18, and the other end thereof engages with the chassis 1. The eject lever 18 is biased by the springs 41L and 41R in the forward direction. Reference numerals 42L and 42R denote fast forward (FF) and rewind (REW) levers, respectively. The FF and REW levers 42L and 42R are biased by springs in the forward direction. Reference numerals 43L and 43R denote operation buttons fixed to the FF and REW levers 42L and 42R, respectively. Reference numeral 44 denotes a lock lever which is slidable to the right and left. When an operator depresses the operation button 43L or 43R coupled to the FF lever 42L or the REW lever 42R, respectively, the lever 42L or 42R is locked in the depressed state by the lock lever 44. The lever 42L or 42R is released from the locked state when the operator depresses the operation button 40 coupled to the eject lever 18. Reference numerals 45L and 45R denote reel shafts which are driven by a motor 46; 47L and 47R, capstan shafts; and 48L and 48R, pinch rollers, respectively. Reference numeral 49 denotes a magnetic head.
The operation of the conventional magnetic recording/reproducing apparatus having the construction described above will now be described. FIG. 1 shows a state wherein the cassette 6 is ejected. In this condition, the cassette holders 5L and 5R are respectively held at the upper positions. The engaging members 24L and 24R of the pivot arms 20L and 20R engage with the notched steps 15L and 15R of the link arms 13L and 13R, respectively.
When the operator inserts the cassette 6 into the cassette holders 5L and 5R, the cassette 6 is guided along the cassette holders 5L and 5R as it is pushed backward. When the operator inserts the cassette 6 further into the cassette holders 5L and 5R, the cassette 6 abuts against the bent members 23L and 23R of the pivot arms 20L and 20R, so that the pivot arms 20L and 20R pivot about the shafts 22L and 22R, respectively. At the same time, the engaging members 24L and 24R pivot upon movement of the pivot arms 20L and 20R, respectively. When the operator further inserts the cassette 6 to pivot the pivot arms 20L and 20R, the engaging members 24L and 24R of the pivot arms 20L and 20R are respectively disengaged from the link arms 13L and 13R, so that the link arms 13L and 13R are pivoted counterclockwise by the biasing forces of the springs 27L and 27R. Since the pins 7L and 7R of the cassette holders 5L and 5R engage with the elongated holes 16L and 16R of the link arms 13L and 13R, respectively, the cassette holders 5L and 5R are guided downward through the guide holes 3L and 4L and 3R and 4R upon movement of the link arms 13L and 13R. As the cassette holders 5L and 5R are moved downward, the cassette 6 inserted therein is also moved downward. The reels (not shown) of the cassette 6 engage with the reel shafts 45L and 45R, respectively. The reels are rotated, so that the magnetic recording/reproducing apparatus is set in the recording or reproduction (play) mode, as shown in FIG. 2. In this mode, the distal ends of the engaging members 24L and 24R of the pivot arms 20L and 20R abut against the inner surfaces of the link arms 13L and 13R, respectively, so that the pivotal movement of the pivot arms 20L and 20R caused by the spring 26 is interrupted.
In the state shown in FIG. 2, when the operator depresses the operation button 40 to move the eject lever 18 backward, the projections 19L and 19R of the eject lever 18 abut against the engaging pawls 12L and 12R of the arms 9L and 9R, respectively, so as to pivot the arms 9L and 9R. Since the pins 8L and 8R of the cassette holders 5L and 5R engage with the elongated holes 11L and 11R of the arms 9L and 9R, respectively, the cassette holders 5L and 5R are moved upward upon pivotal movement of the arms 9L and 9R. In addition, upon this upward movement of the cassette holders 5L and 5R, the link arms 13L and 13R are pivoted. When the link arms 13L and 13R are thus pivoted, the engaging members 24L and 24R of the pivot arms 20L and 20R are separated from the inner surfaces of the link arms 13L and 13R. The pivotal movement of the pivot arms 20L and 20R which was interrupted by the link arms 13L and 13R is now restarted by the biasing force of the spring 26. The engaging members 24L and 24R are brought into engagement with the notched steps 15L and 15R of the link arms 13L and 13R. When the pivot arms 20L and 20R are pivoted, the cassette 6 is urged forward by the bent members 23L and 23R of the pivot arms 20L and 20R, so that the cassette 6 is ejected.
However, in the conventional magnetic recording/reproducing apparatus described above, the cassette 6 is inserted in the cassette holders 5L and 5R and the pivot arms 20L and 20R are pivoted to disengage the engaging members 24L and 24R if the pivot arms 20L and 20R from the notched steps 15L and 15R of the link arms 13L and 13R, so that the cassette 6 is lowered. In this case, the descent timing varies in accordance with dimensional variations and manufacturing errors in the pivot arms 20L and 20R and the link arms 13L and 13R, resulting in inconvenience. In other words, in the conventional apparatus described above, the cassette 6 urges the bent members 23L and 23R of the pivot arms 20L and 20R so as to pivot the pivot arms 20L and 20R. A ratio of a distance between the center of rotation of each of the pivot arms 20L and 20R and a corresponding one of the bent members 23L and 23R to a distance between the center of rotation and the distal end of each of the engaging members 24L and 24R is increased, and the motion of the engaging members 24L and 24R is reduced to a fraction of that of the bent members 23L and 23R when the cassette 6 urges the bent members 23L and 23R to pivot the pivot arms 20L and 20R. For example, when the bent members 23L and 23R are respectively moved by 1 cm, the distal ends of the engaging members 24L and 24R are respectively moved by only 0.2 to 0.3 cm. Since it is this slight movement of the engaging members 24L and 24R and the link arms 13L and 13R which determines the descent timing of the cassette 6, the timing can vary in accordance with any dimensional variations and manufacturing errors in the engaging members 24L and 24R and the link arms 13L and 13R. When the actual cassette descent timing deviates from the correct timing, the cassette 6 catches against the capstan shafts 47L and 47R, the reel shafts 45L and 45R and the like, and cannot be set in the correct position.
In the conventional magnetic recording/reproducing apparatus described above, when the cassette 6 is inserted and lowered (the state shown in FIG. 2), the distal ends of the engaging members 24L and 24R of the pivot arms 20L and 20R respectively abut against the inner surfaces of the link arms 13L and 13R to prevent the pivotal movement of the pivot arms 20L and 20R which is caused by the biasing force of the spring 26. Thus, the stop positions of the pivot arms 20L and 20R fall within a wide range in accordance with the dimensional variations and manufacturing errors in the pivot arms 20L and 20R and the link arms 13L and 13R. For example, even if the position of the distal end of each of the engaging members 24L and 24R varies within a range of only 0.1 cm, the position of the corresponding bent member 24L or 24R may vary within the wide range of 2 to 3 cm. In addition to this disadvantage, the biasing force of the spring 26 always acts on the cassette 6 through the pivot arms 20L and 20R, so that the loading of the cassette 6 becomes unstable. In order to prevent this, the pivot arms 20L and 20R and the link arms 13L and 13R must be adjusted so that the stop positions correspond to the predetermined positions.